1. Field of the Invention
This invention relates to suspensions for mounting powertrain components in a vehicle.
2. Prior Art
Various constructions are known for mounting powertrain components such as an engine and a transmission, in an automotive vehicle. For example, the rear of the powertrain can be mounted on an elongated cross member extending between spaced parallel frame rails of the vehicle frame.
Various couplings between the cross member and the frame rail are known. One such coupling includes the use of bolts directly connecting a cross member to the frame rail of an automobile. Such a non-shock absorbing coupling between the frame rail and cross member is typically used with a shock absorbing cushioning member between the cross member and the powertrain itself. Other couplings betweeen the cross member and frame rail include the use of various rubber members which are in compression.
For example, in prior art FIG. 1, the extremities of a cross member 10 can be relatively blade-like flat terminations which are positioned adjacent a rubber member 11 thereby forming a sandwich-like structure. A bracket 12 is attached to cross member 10 by a bolt 13 and can be coupled to a frame rail. Prior art FIG. 2 has spool-like rubber cushions 20 which have a central axial opening for passing a bolt 21. By coupling cross member 22 to bolt 21 and a frame rail bracket 23 to the exterior of rubber cushion 20, some shock and vibration isolation is provided by the rubber in compression. Prior art FIG. 3 uses rubber bushing 30 having a donut-shape coupled between a cross member 31 and a frame rail bracket 32. The powertrain is mounted on a shock absorbing bracket 33 which is attached to a central portion of cross member 31 and provides additional vibration isolation.
However, such known suspension structures as discussed above, provide only limited vibration and noise isolation. Solid rubber is very difficult to compress and does not provide the desired softness. Further, rubber in compression is difficult to tune to provide desired suspension characteristics. Some attempts have been made at tuning a solid piece of rubber by forming interior voids which provide for some deflection or deformation of the rubber when a load is applied.
The apparently conflicting requirements of vibration isolation and load carrying capacity often do not permit improved vibration isolation because of the need to maintain support of the engine powertrain. It would be desirable to have a suspension system for the powertrain which could be tunable to reduce specific vibrations and yet maintain a load bearing capacity sufficient to support the powertrain. These are some of the problems this invention overcomes.
Various non-linear suspensions are also known. For example, a non-linear wheel suspension includes a pair of spaced walls resiliently supporting a wheel therebetween. An elongated axle extends through opposed openings in the side walls so that the axle has end portions extending beyond the side walls. A wheel is rotationally mounted on the axle between the side walls. A pair of resilient shear discs couple end portions of the axle to an adjacent one of the side plates. Each shear disc includes a pair of spaced cover plates attached to an elastomer therebetween. One of the cover plates is attached to the axle and the other cover plate is attached to one of the side walls so that movement of the axle in a radial direction with respect to the side walls applies a shear force to the intermediate elastomer. A variation of such a wheel suspension includes having cover plates radially offset one from another to provide eccentric openings. An axle passing eccentrically through an opening has more radial suspension travel than an axle going concentrically through an opening of the same size. Thus, for a given size opening in a given size cover plate there is increased travel for an eccentrically mounted axle with respect to a concentrically mounted axle. Additionally, as a result, the wheel is mounted lower with respect to the supported object thus increasing clearance for projections extending from the object toward the wheel as well as for projections extending up from the travel surface of the wheel toward the suspended object. However, there still remains the unsolved problem of providing an improved powertrain mounting in a vehicle.